linjam/JuceLibraryCode/modules/juce_core/threads/juce_WaitableEvent.h

/*
  ==============================================================================

   This file is part of the juce_core module of the JUCE library.
   Copyright (c) 2013 - Raw Material Software Ltd.

   Permission to use, copy, modify, and/or distribute this software for any purpose with
   or without fee is hereby granted, provided that the above copyright notice and this
   permission notice appear in all copies.

   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
   TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN
   NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
   DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
   IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
   CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

   ------------------------------------------------------------------------------

   NOTE! This permissive ISC license applies ONLY to files within the juce_core module!
   All other JUCE modules are covered by a dual GPL/commercial license, so if you are
   using any other modules, be sure to check that you also comply with their license.

   For more details, visit www.juce.com

  ==============================================================================
*/

#ifndef JUCE_WAITABLEEVENT_H_INCLUDED
#define JUCE_WAITABLEEVENT_H_INCLUDED


//==============================================================================
/**
    Allows threads to wait for events triggered by other threads.

    A thread can call wait() on a WaitableObject, and this will suspend the
    calling thread until another thread wakes it up by calling the signal()
    method.
*/
class JUCE_API  WaitableEvent
{
public:
    //==============================================================================
    /** Creates a WaitableEvent object.

        The object is initially in an unsignalled state.

        @param manualReset  If this is false, the event will be reset automatically when the wait()
                            method is called. If manualReset is true, then once the event is signalled,
                            the only way to reset it will be by calling the reset() method.
    */
    explicit WaitableEvent (bool manualReset = false) noexcept;

    /** Destructor.

        If other threads are waiting on this object when it gets deleted, this
        can cause nasty errors, so be careful!
    */
    ~WaitableEvent() noexcept;

    //==============================================================================
    /** Suspends the calling thread until the event has been signalled.

        This will wait until the object's signal() method is called by another thread,
        or until the timeout expires.

        After the event has been signalled, this method will return true and if manualReset
        was set to false in the WaitableEvent's constructor, then the event will be reset.

        @param timeOutMilliseconds  the maximum time to wait, in milliseconds. A negative
                                    value will cause it to wait forever.

        @returns    true if the object has been signalled, false if the timeout expires first.
        @see signal, reset
    */
    bool wait (int timeOutMilliseconds = -1) const noexcept;

    //==============================================================================
    /** Wakes up any threads that are currently waiting on this object.

        If signal() is called when nothing is waiting, the next thread to call wait()
        will return immediately and reset the signal.

        If the WaitableEvent is manual reset, all current and future threads that wait upon this
        object will be woken, until reset() is explicitly called.

        If the WaitableEvent is automatic reset, and one or more threads is waiting upon the object,
        then one of them will be woken up. If no threads are currently waiting, then the next thread
        to call wait() will be woken up. As soon as a thread is woken, the signal is automatically
        reset.

        @see wait, reset
    */
    void signal() const noexcept;

    //==============================================================================
    /** Resets the event to an unsignalled state.
        If it's not already signalled, this does nothing.
    */
    void reset() const noexcept;


private:
    //==============================================================================
   #if JUCE_WINDOWS
    void* handle;
   #else
    mutable pthread_cond_t condition;
    mutable pthread_mutex_t mutex;
    mutable bool triggered, manualReset;
   #endif

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (WaitableEvent)
};


#endif   // JUCE_WAITABLEEVENT_H_INCLUDED